High speed contacting device



E. J. DIEBOLD HIGH SPEED CONTACTING DEVICE Aug. 30, 1960 7 Sheets-Sheet1 Filed Jan. 10, 1956 Aug. 30, 1960 E, J. oli-:BOLD

HIGH SPEED CONTACTING DEVICE '7 Sheets-Sheet 2 Filed Jan. lO, 1956INVENTOR.

Aug. 30, 1960 E.IJ. DIEBOLD v 2,951,188

HIGH SPEED coNTAcTING DEVICE Filed Jan. l0, 1956 7 Sheets-Sheet 3 EE-.7.g5- 5.

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E. J. DIEBOLD HIGH SPEED CONTACTING DEVICE 7 Sheets-Sheet 4 -AZZ Aug.30, 1960 Filed Jan. 1o, 195e Allg- 30, 1960 E. J. DIEBOLD 2,951,188

HIGH SPEED coNTAcTING DEVICE Filed Jan. lO, 1956 7 Sheets-Sheet 5 Apg.3o, 1960 E. J. DIEBOLD 2,951,188

HIGH SPEED CONTACTING DEvxcE Filed Jan. 10, 1956 7 Sheets-Sheet 6INVENTOR. 50M/iff) JU//A/D/Ezmu BYMM/ my Aug. 30, 1960 E. J. DIEBOLDHIGH SPEED CONTACTING DEVICE '7 Sheets-Sheet 7 Filed Jan. l0, 1956United States Patent ii [ice Patented Aug. 30, i960 HIGH SPEEDCONTACTING DEVICE Edward J. Diebold, Ardmore, Pa., assignor to I-T-ECircuit Breaker Company, Philadelphia, Pa., a corporation ofPennsylvania Filed Jan. 10, 1956, Ser. No. v558,349

14 Claims. (Cl. 317-156) My invention relates to a high speed contactingdevice in which a unitary structure serves as both a movable contact andas an electrical winding whereby current through the lelectrical windinginteracts with an operating magnetic eld to effect motion of the unitarystructure.

In the past, an attempt has been made to utilize the repulsive orattractive interaction between two current carrying coils to effect themotion of a movable contact orf a contact device. These previousattempts, however, have proven to be unsuccessful since a separatecontact and two individual coils were used whereby one of the coils wasattached to the movable contact and upon energization o-f the secondcoil the entire movable contact and coil had to be accelerated toachieve circuit interruption. It is to be realized, however, that thisprior concept required the acceleration of a relatively high mass ofboth a coil `and a movable contact. In view of this relatively highmass, the 'forces required to achieve a given acceleration becomeprohibitively high, too high for any known material to withstand. Thislimits the possible acceleration to a low value, which limits the valueof the device. Besides the material limitation there is also thenecessity of accelerating a large mass which requires a prohibitivelylarge amount of electrical power for the enengization of the activatingcoil.

In accordance with the principles of my novel invention, I overcome thisrelatively high movable mass which must be accelerated by providing aunitary structure for both the movable contact and the electricalwinding which accelerates this movable Contact to a predeterminedcontact position responsive to the energization of an perating means,such as another winding.

More specifically, the movable contact which may be a ring-shapedconductor can make contact with stationary conductors along the surfaceof a cone and a circuit is opened or closed at the contact surfaces. Thering-shaped movable contact is further positioned to be closely situatedto an operating winding so as to obtain good coupling between theoperating winding and the winding formed by the ring shape of themovable contact and the operating winding is energizable 'by a strongcurrent of very high frequency.

lf now the primary winding is energized, -as by means of the dischargeof a capacitor, an extremely high current of opposite direction and same`frequency will be induced in theringashaped contact. A repelling forceis then existent between the coils which increases with the square ofthe current flowing therethrough. Since, however, this force is neededfor only a very short time, an exceedingly high current is permissiblebecause of the short time it flows in which coil heating takes place.

In view of the extremely high permissible current, tremendous forcescome into play in accelerating the movable contact with respect to thestationary contacts. Because of the unitary structure ot winding and contact, such as a solid ring of metal, the tremendous forces do notrequire any means of transmission of force, i.e. no movable structuralparts are needed. Hence, no limits are encountered due to the limitedstrength of the ma'-A terials which are being used.

Because of this tremendous acceleration imparted to the movable contact,the instantaneous break-down voltage between the movable contact and itscooperating contact will always be greater than the instantaneousrecovery voltage that appears across these separating contacts. Thiseffect may be enhanced by operating my novel contact device in anatmosphere under a high pressure in order to increase the dielectricstrength between the separating contacts and thereby increase theinstantaneous break-down voltage. Clearly by providing a system in whichthe instantaneous break-down voltage between the separating contactsWill always be greater than the recovery voltage thereacross, an arcwill not be formed and arc extinguishing means need not be provided.

In the event of the formation of [an arc, if the contacts are separatedslightly prior to `a zero current value, the magnetic field in theregion of the arc will be in such a direction as to cause the arc torotate rapidly around the vertical axis of the coils. Hence, the `arc isburning v on relatively cool electrodes and upon passage of the cur-rentthrough zero, the arc will extinguish.

I have found that due to the inherently low coupling .between theoperating winding and the movable winding, that the eiiiciency of mynovel system is low. This may be appreciably increased, however, byproviding a ferrite core to extend through the two coils and appreciablyincrease the etiiciency of the system.

Accordingly, it is -a primary object of my invention to provide a highspeed contacting device wherein the acceleration imparted to a movablecontact is such that the instantaneous 'breakdown voltage betweenseparating contacts is always greater than the instantaneous recoveryvoltage across the separating contacts.

Another object of my invention is to provide a movable contact for ahigh `speed contacting device which is so constructed as to cooperatewith a second contact for contacting purposes as well as to provide anelectrical winding for cooperation with an operating magnetic field.

Still another object orf my invention is to provide a high speedcontacting device wherein a unitary structure serves as a movablecontact which is so shaped as to form an electrical winding and to thenprovide a second Winding which is energizable responsive topredetermined electrical 'conditions to thereby induce a current in theabove-mentioned movable contact, which current shall be effective tocreate a magnetic iield which will repel the magnetic field of therelatively stationary winding to move the movable Contact towards a newposition.

Still vanotherobject of my invention is to provide a high speedcontacting device wherein a unitary movable contact and sho-rt circuitedwinding interacts with an operating winding whereby energization of theoperating winding effects motion of the movable contact and the completesystem operates under a high pressure gas to thereby increase thedielectric constant between the separating contacts. Y

The operating winding of my novel invention may be formed of a conductorwhich is relatively thin and wound in the form of a spiral or pancake inwhich the height of the conductor is substantially larger than itsradial diameter. If now a capacitor discharge is used for energizationof the operating winding, it is to be realized that this discharge willbe of an extremely high frequency.

The novel movable Contact of my invention may be constructed in asimilar way which, by way of example, could be a single turn or ring inwhich the height of the turn has a dimension of the same order ofmagnitude or greater than the radial diameter of the turn. When a highfrequency current is induced in this movable contact due to a current inthe operating winding, `it is understood that this current will be ofthe same high frequency as that in the operating winding. vIn view ofthis extremely high frequency, the so-called proximity effect will bevery great.

As is well known, the proximity effect in the case of two closelycoupledcoils will cause the current in each coil to have a current`density of unequal value throughout the cross-sectional area of thecurrent conductors. More specifically, more current will flow throughthe copper cross-sectional area of the conductor which is in closerproximity to the coil with which it is interacting. In 'View of thiseffect, it is, therefore, seen that the effective distance between coilswill be decreased to thereby increase the coupling between-coils and therepelling force which is inverselyproportional to the square of thiscoupling distance.

Accordingly, another object of. my'invention is to construct at leastone of the operating windings or the movable winding of my novel Yhighspeed contact device in such a manner that proximity effects will bebrought into play to'thereby increase the coupling between the coils. wAnother object of my invention is to provide 'an operating winding whichis formed of a spiral winding wherein the height of the conductor usedis substantially larger than its radial diameter to thereby introduce anappreciably large proximity effect due to the high `frequency dischargeof an energizing capacitor.

Still another object of my invention is to form both the operatingwinding and the movable Contact of my novel high speed contact device insuch la manner that the height of the conductors forming these windingsis substantially comparable to or greater than the radial diameter ofthe conductors, whereby proximity effect is brought into play toincrease the coupling between the operating winding and the movablecontact.

After contact separation, the movable contact is moving withconsiderable momentum, and it'must be braked to a stop 'and eithermaintained in a disengaged position or be allowed to return to thecontact engaged position. For this purpose I provide a novel brakingcylinder or chamber which has an internal cross-sectional configurationwhich will receive the shape of the movable contact ring. Hence, thecontact ring, which may be guided into the cylinder by means'of a postextending through its center, will upon entering the cylinder begin tocompress the air between the ring and the opposite end of the cylinderwhich is enclosed. AsA the air within the cylinder is 'compressed bythemotion of the contact ring therein, it is seen that a force is developedwhich is in a direction to oppose the motion of the ring.V

Furthermore, if the contacting device is operating under a high gaspressure in order to achieve a high dielectric constant between theseparating contacts, it is clear that this opposing force willbe greatlyincreased.

When the kinetic energy ofthe movable contact is finally completelytransferred to compress the air between the movable contact and theenclosed end of the cylinder, it is to be realized, that a force willnow be exerted by this compressed air to accelerate the movable contactin the opposite direction. i

ln order to prevent this rebound ofthe movable contact, I provide anannular depression in the cylinder wall which is so disposed that uponpassage of the movable contact, a port will be available 'to allow theescape of the compressed air between the movable contact and the end ofthe cylinder wall. After s o relieving the compressed `air capturedbetween the movable contact and the end of the cylinder, the contact maybe latched in a disengaged position or, if desired, the contact may beallowed to return to its engaged position under the eiect of a biasingforce, such as gravity or a spring means.

Accordingly, another object of my invention is to provide a brakingmeans for dissipating the kinetic energy of Another object of myinvention is to provide a braking means for the novel movable contact ofmy invention which is comprised of a cylinder having an enclosed end anda cross-sectional area of a shape which will cooperate with thecross-sectional area of the movable contact.

Another object of my invention is to brake the motion of a movablecontact by bringing it into an enclosed cylinder and allowing it tocompress the air between the enclosed end of the cylinder and thecontact ring itself whereby forces due to the pressure of the compressedair tend to retard the motion of the contact ring.

Another object of. my invention is tov gui-de the movable contact into acylinder having an enclosed end and an annular recess in the interiorthereof whereby compressed air between the enclosed end of the cylinderand the contact ring itself is allowed to escape when .the contactpasses this annular recess. Y

it has been described above thatr thev motion of the movable contact maybeV braked and the movable contact is thereafter allowed to return toits former position after contact disengagement has ytaken place betweenthe movable contact and its cooperable Contact. lf this is` the case andit is desirable to prevent contact engagement, it is possible to movethe cooperating contact, which may be `a'pair of relatively stationarybridging contacts, toa remote position responsive to movement of themovable Contact to a disengaged position.

This withdrawal or movement of the stationary contacts toy a yremoteposition after contact disengagement may in fact be necessary to defeata second cont-act engagement in case reclosing or" the circuit is to beavoided. In an actual structure, it is to be realized that thestationary contacts are biased into engagement with the movable VContactto obtain high contact pressure. rihis biasing may be accomplishedl by aspring means or any other desired means. However, upon disengagement ofthe contacts, a rather high force would have to be brought into play inorder to rcengage tbecooperating contact by overcoming the biasing meansof the relatively stationary contacts.

The withdrawal of the stationary contacts has the advant-age of makingthe circuit breaker trip free, ie. then the circuit breaker opens underthe action of the movable Contact being expelled violently, thestationary contacts are thereafter retracted leaving the circuitbrcalrer open when the movable contact assumes the closed positionagain. Closing of the circuit breaker is effected by pushing thestationary contacts .adjacent `he movable contact. When closing againsta fault, the movable con-- tact can be expelled without delay. i

This withdrawal of the stationary contactarme-.y be accomplished byvarious types of hydraulic or electromagnetic means I.which areenergized responsive to the motion of `the movable contact or, ifdesired, responsive to the means which energizes the operating winding.Y

Still another manner in which withdrawal of the stationary contacts, maybe effected is by ,utilization of the compressed air` inthe breakingcylinder. of the movable contact.

Accordingly, :an important objectA of my invention is to provide meanswhereby the contact cooperating with the movable contact is. soconstructed. that it may be removed or withdrawn from the contactengaging larea responsive to disengagement or motion of the movablecontact, Y Y v v Y 'f Another object ofvrmy invention is to provide.bridging stationary contacts forthe. movable Vcontact ring of myinvention which aresoconstructed. -as to., bek normally biased intocontact engagement with the movable contact ring and are withdrawn oyhydraulic, pneumatic or electromagnetic means responsive to Contactdisengagement.

It has been seen that my novel high speed contact device cansuccessfully interrupt circuits which may have extremely high shortcircuit capacities land very high rates of recovery voltage because thecooperating contacts separate so fast that the instantaneous breakdownvoltage is always higher than the instantaneous recovery voltage.

Clearly, it is desirable to reduce the rate of rise of recovery voltageif possible, and this is possible by connecting a capacitor across thecontacts. By a further extension of this idea to the case in which Iapair of stationary contacts are utilized and the movable contact ringcomes into bridging contact engagement therewith, I have found that byconnecting a center tapped capacitor in series with the stationarycontacts and connecting the center tap to the movable contact, I obtainan equal distribution of the recovery voltage across the two breaks ofthe contact device, reduce the rate of rise of recovery voltage and`also partially elimina-te the high frequency oscillations causing theextremely 'high recovery rates.

Accordingly, a still further yobject of my invention is to utilize acenter tapped condenser in conjunction with a contacting deviceconstructed in accordance with my novel principle in which a pair ofstationary contacts are utilized for bridging contact cooperation with amovable contact ring wherein the outer ends of the condenser areconnected in series with the stationary contacts and the center tap ofthe condenser is connected to the movable contact to thereby decreasethe rate of rise of recovery voltage, equally distribute the recoveryvoltage across the two Vbreaks `and partially eliminate the highfrequency oscillations which cause high rate of rise of recoveryvoltage.

When utilizing an operating winding which -is energized by the dischargeof a capacitor, it is desirable to have this energiza-tion take placefor a subsequent contact disengagement immediately prior to a zerocurrent value in the circuit being protected. This is extremelydesirable, iirst, because lthe interrupting duty on the disengagingcontacts is decreased and, secondlyany arc which is formed willextinguish when the current subsequently passes through the zero currentvalue. This is particularly true in the case of my novel device sincethe arc will move extremely rapidly around the axis of the movablecontact and will be in contact with this relatively cool body.

I, therefore, provide a novel trip circuit which in effective to connecta charged capacitor to the operating coil a timeimrnediately prior to aninstantaneous zero current value regardless of the current value atwhich the fault occurs `on the circuit. 'Ihfat is to say, if the faultoccurs during a relatively high instantaneous current value, the trip isdelayed until this current value, in the case of `an A.C. circuit,decreases to substantially zero value. Obviously, this same principlemay Ibe utilized for a reverse current -trip in the case of a D.C.circuit.

More specifically, I provide a trip circuit in which the line current ismeasured with a current transformer and the output of the currenttransformer is connected to a saturable reactor which in turn deliversan output pulse Slightly prior to -a measured zero current value of thecurrent transformer. The pulse circuit is then connected in series witha fault sensing device which upon occurrence of a fault allows the pulsewhen created to operate a lswitching means which in turn connects acharged capacitor to the operating winding of the contact device. Hence,the operating winding is energized immediately prior to the rst zerocurrent value after the occurrence of a fault.

Accordingly, another object of my invention is to provide a trip circuitfor connecting a capacitor to the operating winding of my novelcontacting device only immediately prior to a zero current value throughthe cooperating contacts irregardless of the instantaneousr currentValue' at which a signal is given to operate the contacts at adisengaged position.

Another object of my invention is to provide a trip circuit which is soconstructed as to force a current transformer which measures the circuitcurrent to deliver a pulse slightly prior to a zero current value whichpulse is connected -to a switching means which in turn connects thecharged capactor to the operating winding to thereby operate thecontacting device only prior to a zero current value irregardless of thecurrent value at which the signal to operate the contact device takesplace.

All of the preceding objects and many others will become apparent whentaken in conjunction with the description in which:

Figure l shows a cross-sectional view of one embodiment of my novelinvention.

Figure la shows my invention in a schematic form to more specificallyillustrate the principles of its operation.

Figure 2 shows a view taken across the lines 2-2 of Figure 1.

Figure 3 shows a view taken across the lines 3-3 of Figure 1.

Figure 4 shows a second embodiment which may be assumed by the novelunitary movable contact and short circuited winding of my novelinvention.

Figure 5 shows a top view of the novel contact of Figure 4.

Figure 6 shows a view taken along the lines 6-6 of Figure 1 tospecifically illustrate the manner in which the stationary contact maybe fastened to the input current conductors and still he able towithdraw the stationary contact subsequent to contact disengagement.

Figure 7 shows an embodiment of a stationary contact structure whichdiffers from that seen in Figure l.

Figure 8 shows another embodiment of my novel invention.

Figure 9 shows an embodiment of a structure which may be used to supportan operating winding.

Figure 10 shows a tripping circuit which in accordance with my novelinvention may be used to energize an operating winding only at a timeimmediately prior to a zero passage of current through the cooperatingcontacts.

Figure 11 shows a schematic illustration of my novel invention wherein apair of stationary contacts are bridged by a movable contact and acenter tapped condenser is connected to distribute the recovery voltageequally on both breaks of the bridging contact arrangement.

Figure 12 shows a still further object of my invention.

Figure 12a shows a View of the contact structure ot the embodiment ofFigure 12.

Figure 13 shows a schematic View of one application of the embodiment ofFigure 12.

Figure 14 shows a schematic view of another application of theembodiment of Figure 12.

Figures 15a, 15b and l5c show current time characteri istics for theoperation of the circuit of Figure 13.

Figure 16 shows a graphical representation of the operation of my noveldevice.

The basic principle of my novel invention may be more thoroughlyunderstood with reference to the schematic drawings of Figure la. Figure1c: shows a source of electrical energy 20 as being connected in serieswith a load 21 and a contact device indicated generally at 22. Thecontacting device is comprised of a pair of stationary contacts 23 and24 which are schematically shown as being bridged by a movable contact25 which, as well as being the movable contact, comprises a shortcircuited winding.

A second winding or operating winding 26 is positioned with respect tothe coil 25 in such a manner that energization of the coil 26 willinduce a current in the coil 25 and their mutual magnetic iields will bein such a direction as to drive the coil 25 away from the coil 26 andout of engagement with the stationary contacts 23 and 24,

The operating coil 26 is `further shown as being connected in serieswith a capacitor 27 which is maintained in. a charged Condition by theRC2-Source 2,8- A Switchingmeans 29 is then provided to selectivelyconnect the charged capacitor 27 in series with the coil 26 at anydesired time. The switching means 29 may, if desired, be operatedresponsive to a predetermined electrical condition and the circuitsupplied by the energy source 20, and as will be shown hereinafter, maybe further constructed as to discharge the capacitor 27 through4 coil2.6 only4 immediately prior to a zero current value through the contactstructure 22. One possible embodiment of a contacting device which willoperate in accordance with the principle set forth in conjunction withFigure la is shown in Figures l, 2 and 3. More specifically, Figures land 2 speciiically show a pair of relatively stationary contacts or sideconductors 3@ and 31 which are biased into contact engagement with themovable ring contact 32 by means of the biasing springs 33 and 34,respectively. As will be described more fully hereinafter, the sideconductors 30 and 3l are so constructed as to be withdrawable to` adisengaged position responsive to movement of the movable ring` contact32 to a disengaged position.

Itis seen in Figures l and 2 that the moving ring contact 32 has theshape of a at disc and is guided by a cylindrical rod 35. The ringcontact 32 may be con structed of a hard aluminum material with silverplated contact surfaces on its circumference. The edges of all theContact surfaces are well rounded in order to prevent spark over betweensharp points of the movable contact and the stationary contact. As isseen more specifically with respect to Figure 2, the side contacts 30and 31 are constructed Vto have rounded portions so that they may fitclosely upon the cylindrical part of the ring and provide asubstantially large contact area.

The side conductors 30 and 31 may be made of a bronze material withsilver plated contact surfaces for cooperation with the contact ring 32.Since the side contacts 30 and 31 are to be movable out of the area ofcontact engagement with respect to the ring contact 32, these sideconductors are connected to the outer conductors 36 and 37,respectively, by means of the identical brush arrange' ments showngenerally asv brush assemblies 38 and 39, respectively, in Figure l'.

This brush arrangement which mayy be specifically seen in conjunctionwith Figure 6 is comprised of a plurality of brush members 4t) which areVbiased into engagement with the side conductors 30 and 31 by means ofthe springs 41 which also maintain the brush member 4t) in the groove 42of the conductor 36and the groove 43 of the conductor 37.

It is to be noted that the conductors 36 and g3? may be so constructedas Vto complete a generally air-tight housing around the variouscomponents of the Contact device. In this case, it would` then bepossible to operate the device under a high gas pressure whereby thedielectric strength between separating contacts would be increased. Thisgenerally air-tight structure is shown as comprising cylinder 43, hollowmember 44, hollow member 45, the conductors 36 and 37 andthe base member46. Hollow members 44 and 45 are insulating material to therebyelectrically insulate side conductorsv 3l?l and 3l. The air is furtherprevented from escaping froml between the side conductor 3l? and theconductor member 35 by means of the gasket 47 and similarly a gasket 48is provided to prevent air escape between the side conductor 31 and theconductor member 37.

The operating coil or the winding which 4is operative to cause motion ofthe movable contact ring 32 isr seen in Figures l and 3 as` comprisingthe spirally wound winding 49 which is embedded in a supportinginsulating material shown as the cross-hatched portions 50. Theoperating `winding assembly is then positioned` on top of la block ofinsulating material 51' anda capof insulating material 52 is then boltedby means of the bolts 53 and 54 in such a manner. as to securelymaintain the spiral winding 49 on top of the insulating block 5l. Thetop of the cap 52 may then be used as a seat for the contact member 32when it is in the normally engaged position and further provide for anaccurately controlled minimum separation between the contact ringwinding 3 2 and the spirally wound operating winding 49.

Figure 3 specifically indicates the manner in which the leads of thespirally wound operating winding 49 are taken out of the air-tightenclosure housing the contacting device. That is to say, the leads maybe taken out through the common tube 55 which is taken through a gasket-56 and the air-tight seal shown generally at 57 is being maintained tothe housing 43 and 46 by means of the bolts 5t; and 59. This allows theleads to be positioned nextV to one another to thereby maintain a smallleakage reactance.

The operating Winding support 51 is, in Figure l, further seen to beconstructed to contain the springs 6b and 6i which maintain thestructure 51 at a predetermined distance from the top of the base member46. ln effect, the springs 6 0 and `61 serve a shock-absorbing function.For when the operating winding 49 is energized to drive the ring contact312 to a disengaged position, it is to be realized that an equal andopposite effect will be imparted to the operating winding assembly 5l.By providing the springs 60 and 61, this shock or impulse is more easilyabsorbed without breakage of any of the associated components. Y

Pneumatic cushioning is also provided forshock-absorbing purposes sincethe air in the space between the operating winding support `Slt and thebottom member 46 is compressed. This compressed air may then be slowlyexhausted through the ports 62 and 63 at the sides of the structure 51.

It is now understood, in view of the discussion of the operation ofFigure la, that when the operating coil 49 of Figures 1 and 3 isenergized, as by the discharge of a capacitor, an extremely high currentwill be induced in the ring 32 and this ring will be driven away fromthe spiral winding 49 to a disengaged position with respect to the sidecontacts 30 and 3l. It is, however, necessary to prov-ide a means toabsorb the energy of the ring contact 32 once the contact disengagementhas been eiiected. This energy absorbing means is shown in Figures 1 and3 as the cylinder 43.

More specifically, the cylinder 43 has an internal crosssectional areawhich will cooperate with the shape of the movable contact 32. Hence, inthe case of the contact 32 which'has a substantially -circular shape,the internal cross-sectional area ofthe walls 64 of the cylinder 43 willhave a corresponding circular shape.

Therefore, when the ring contact 32 is driven away from the operatingwinding 49 by their mutual magnetic fields, the ring contact 32 willenter the cylinder 43 and compress the air, which may already be in ahighly cornpressed state, between the top surface of the movable contact32 and the enclosedV portion 65 of the cylinder 43. ln view of thiscompression, a force will develop tending to retard the motion of themovable contact 32. That is to sa` the kinetic energy ofl the ringcontact 32 will be transferred to the compressed gas within the cylinder43.

When, however, a complete transference of energy takes place, it is seenthat the ring contact 32 will now be driven back towards the position ofcontact engagement by means of the compressed air within the cylinder.YIn order to avoid this, an angular depression or recess 66pis providedwithin the cylinder wall l64 so that upon passing this angulardepression 66, a port will be formed between Vthe depression 66 andthemovable contact 32 to allow the escape of compressed air between themovable conf tact 32and the enclosedend 65 of the cylinder 43. in viewof this exhaust of the gas, which is at a higher pressure than the gasat the bottom of contact 32, it is seen-that a great deal of the reboundforce will be exhausted. Upon continued travel past the angulardepression 65 and toward the enclosed end 65, the remainder of thekinetic energy of the movable contact 32 will be exhausted in a furtherbut much smaller compression of the air captured between the contact 32and the enclosed end of the cylinder `43. p

In view of this slighter compression of air, the ring contact 32 will bebrought to a standstill and eventually thrown back to pass the angulardepression 66 with substantially the same velocity with which it hadpassed it in the opposite direction. After passing the port 66, however,it is to be realized that a decompression will take place within thecylinder 43 until the contact 32 emerges therefrom. This decompressionwill serve to decrease the velocity of the ring contact 32 until itsubsequently is returned to the original contact engaged position at avery low velocity.

If desired, the angular depression 66 could have been replaced by avalve means whereby air is allowed to escape or is brought into anothersection of the apparatus. In this case, as is true of the previouslydescribed case, it would be possible to absorb the complete kineticenergy of the movable contact 32' and to thereafter latch it or maintainit in a disengaged position when it reaches a predetermined distance ofseparation from the cooperating contacts 30 and 31.

If, however, the contact 32 is allowed to return to its originalposition as has been described in conjunction with the structure shownin Figures l, 2 and 3, it would be extremely undesirable to allowcontact engagement to reoccur between the contacts 30 and 31 since thiswould reestablish the disengaged circuit.

If this is to be avoided and if the contact 32 is not to be latched ormaintained in a disengaged position, I propose to so construct the sideconductors 30 and 31 that they are moved or withdrawn to a remoteposition responsive to the motion of the contact 32.

In Figure 1, compressed air supplies 67 and 68 are schematically shownas being connected to the ports 69, 70, and 71, 72, respectively. It is'to be noted that the channel 70 will lead compressed air into the space73 between the side of .the conductor 36 and the piston 74 of the sideconductor 30 and similarly, the channel 72 will lead compressed air intothe space 74a which lies between the wall of the conductor 37 and thepiston 75 of the side conductor 31. If, therefore, the valves shownschematically as valves 76 and 77 of compressed air supplies 67 and 68,respectively, are operated simultaneously with the energization of thecoil 49 for moving the movable contact 32 to a disengaged position, thenit is seen that compressed air will ow into the openings 73 and 74a tothereby drive the pistons 74 and 75 in a direction away from' the areaof contact engagement with the contact 32. By providing the gaskets 78and 79 for the side conductor 30 and the gaskets 80 and 81 for the sideconductor 31, it is seen that this compressed air which is used to drivethe side conductors 30 and 31 to a removed position may not escape frombetween the housing members 82 and portion of 83 of the side conductor30 and similarly from between the housing member 84 and portion 85' ofthe side conductor 31.

When it is desired to close the circuit once again, it is only necessaryto defeat the compressed air supplies 67 and 68 whereby biasing springs33 and 34 will move side conductors 30 and 31 back into engagement withthe movable contact 32 which rests on insulating cap 52. Closing thecircuit breaker by moving the stationary side contacts into engagementwith the movable contact situated in its rest position of the closedbreaker, permits to interrupt a short circuit at closing by expellingthe movable contact even while the stationary side contacts are still inthe closing stroke. Hence, the circuit breaker is trip free.

It is to be noted that this eiect could be similarly 10 obtained in theabsence of the compressed air supplies 67 and 63 by leading the air,which would be compressed in fthe cylinder 43 by the motion of themovable conductor 32, to the openings 74a and 73.

lt is obvious that many modifications of the components shown in thecontact device of Figures 1, 2 and 3 are possible and come within thescope of my novel invention. By way of example, the movable contact ring32 of Figure 1 could have assumed the shape shown in Figures 4 and 5which show a contact ring 90 having an annular contact 91 and contactsurfaces 93 and 94 which could cooperate with side conductors.Obviously, contact surfaces 93 and 94 could be along any circumferentialportion of fthe ring 90. In the case of the movable contact of Figures 4and 5, it is seen that no sharp edges are provided which would allowflashover between the movable contact and cooperating stationarycontacts. Similarly, the cut away portion 91 allows a more rapidincrease in separation between the movable contact 90 and its coperatingstationary contact than would a contact having the shape of contact 32of Figure l. Hence, the rate of rise of ilashover voltage is increased.

The support block 51 of Figure l which supports the spiral winding 49could have been constructed as shown in Figure 9 of an upper insulatingsection 95 and a lower section of high density material 96. The twosections 95 and 96 may then be maintained together by a bolt means whichserves a dual function by extending through the openings 97 and 98 tofasten a top cap such as the cap 52 of Figure 1 which would in turnmaintain the spiral winding or operating winding to the insulated block95 of Figure 9. By so providing this additional mass, it is seen thatthe shockaabsorbing` properties of the structure are enhanced since agreater mass must be accelerated by the same force. Hence, theacceleration of the composite block 95, 96 of Figure 9 would be lessthan that of the block 51 of Figure l and stress problems would bereduced accordingly.

The side conductors 30 and 31 could be modified so that they may operateon an underpressure principle for withdrawal to a remote position aftercontact disengagement as is shown in Figure 7 with reference to sideconductor 31. Obviously, side conductor 30 could be constructed in anidentical manner. In the case of Figure 7, it is seen that the space 74awhich lies between the conductor 37 and the piston member 75 is, becauseof the ports 100 and 101, at the same pressure as is the rest of theinterior of the contacting device. Similarly, the ports 102 and 103allow the space containing the spring 34 to be under the same pressureasis the rest of the apparatus. This is clearly distinguished from thecase of Figure 1 in which the space 74a was, in view of the gaskets 48and 80, ata much lower pressure than was the rest of the apparatus.

In the case of Figure 7, however, it is seen that the space defined bythe end portion 84 of the side conductor 31 and the housing member 104are at a pressure defined by the pressure of the compressed air supply105 when piston 106 is positioned to bring port 107 into engagement withboth passages 108 and 109. Hence, pressure conditions during normalcontact engagement in the case of Figure 7 will have the side conductor31 biased into engagement with a movable ring contact by both the spring34 and the pressure of compressed air supply 105.

Plunger 106 is movable within the cylinder 110 by means `of a coil 111when the coil is energized by an electrical voltage source 112. A relayshown generally at 113 is then provided to have a coil 114 and a pair ofcontacts seen generally at which are engaged to thereby connect thevoltage source 112 to the coil 111 upon energization of the coil 114from the terminals 116. Upon contact engagement of the contacts 115, thecoil 111 is energized and the plunger 106 will be rapidly moved to theright to thereby bring the port 107 out of 11 registry with the airpassage 108' and allow the air passage 108 access to the open end 117 ofthe cylinder 111i. Under this condition, it is seen that the pressureupon the end 84 of the side conductor 31 is substantially reduced andthe pressure in the volume 74a which is at the relatively high pressureunder which the system operates `is then sufficient to drive thecomplete assembly away from the area of contact engagement.

If, therefore, the terminals 116 are electrically cone nected to beenergized responsive to the same electrical conditions whichactuate therenergization of the operating winding, such as the operating winding ofFigure 1, then it is clearly seen that the side conductor 31 will bemoved away from the area of contact engagement at the same time thatcontact disengagement takes place. Hence, upon subsequent return of themovable contact to its original position, a re-engagement of thecontacts Will not occur.

Figure 8 illustrates a second embodiment which could be taken by thecircuit interrupting device of Figure l. In the case of Figure 8,however, the movable ring contact 121i completes an electrical pathbetween current carrying side conductors 121 and 124 which may beconstructed in the same manner as was side conductor 31 of Figure 1, andthe contact post 122 which conducts the current to a terminal 123. Sideconductors 121 and 124 may be part of .an arrangement of radial sideVconductors forming a pattern similar to the one shown in Figure 6carrying current radially over the Whole ring.

The current carrying member 122 is further provided with a recessedportion 125 which acts as did the cylinder 43 in the case of Figure l toabsorb the kinetic energy of the movable contact 121i. If desired, therecess 125 may be provided with an angular depression which will act inthe same manner as did the angular depression door Figure 1 in order toallow the movable contact 1241 to return to its original position atsubstantially a zero velocity. Figure 8 further shows a spiral woundoperating winding 1245 which in this case'is shown as being embedded ina ymaterial such as an epoxy resin.

The epoxy resin suppont 127 further encloses the leads 131B and 131 ofthe spiral winding 126 outof the support member 127. Y

It is further seen in Figure 8 that the lead 131 comes directly out tothe terminal 132 while the lead 13@ which is terminated at the terminal133 is interrupted by the air gap shown generally at 134. Within the air134 and connected to terminal 135 is disposed an auxiliary electrode 136which is so constructed that when. a sufficient potential is impressedbetween the terminalsV and 135 a ilash over Will occur between theelectrones 136 and 137 to thereby ionize the air within the air gap 134.

Upon this ionization, it is seen that the electrode 13S of the conductor131B and the electrode 137 ofrthe conductor 130 `are electricallyconnected by virtue of the ionized air within the air gap 134.

Therefore, if a chargedV condenser is connected across the terminals 132and 133 and the signal to initiate centact disengagement between thecontacts 121B and 123i of Figure 8 is impressed across the terminals 133end 135, then upon this signal, the air gap V134 will be broken down andthe charged condenser will be allowed -to discharge into the winding 126to thereby eiect contact disengagement. i

It has been previously mentioned `that in order for my novel high Vspeedcontact device to work eectively, that the instantaneous breakdownvoltage `between the separating contacts must be greater than theinstantaneous recovery voltage at all times. By placing a condense-racross the separating contact, the rate of rise of the recoveryyoltageywill be` decreased... in the case of a contact device having` a pairof, stationary contacts which are bridged by a movable contact, I havefound that by utilizing a center tapped condenser and connecting thecondenser across the stationary contacts and connecting the center'tapto the movable contact that I can equally distribute the recoveryvoltage across each break.

' lf this were not the case, itY would then be possible that therecovery voltage would not be equally distributed and that theinstantaneous recovery voltage across the break of one of the stationarycontacts and the movable contact would be higher than the flash overvoltage to thereby create a destructive arc.

T his novel principle is schematically shown in Figure 1l wherein acapacitor 141) is connected across the side conductors or contacts 141and 142 which are assembledV in the insulators 143' and 144. The movablecontact 145 is then shown as being guided on a conductive guide post 146which is in turn connected to the center tap 147 of the condenser 141B.By so forming this connection, I can now assure that the instantaneousrecovery voltage between the side contact 141 and the movable contactand the side contact 142 and the movable contact 145 will be equallydistributed. Similarly, the capacitor, when so connected will tend tosmooth the higher harmonics of the recovery voltage Iwhich are primarilyresponsible for the high rate of increase of this recovery voltage. Y

lt has been previously mentioned that a tripping circuit would bedesirable such that contact disengagement occurs slightly prior to aZero ciurent value. Figure l0 presents a novel circuit that willaccomplish this end wherein the capacitor 150 serves to dischargethrough an operating winding 151 to thereby impart a repelling force tothe unitary contact and coil 152 which connects the stationary contactsshown schematically as 153 and 154.

In Figure l() it is seen that the operating coil 151 could correspond tooperating coil 49 of Figure l, the movable contact 152'could correspondto the movable contact 32 of Figure l, and that the stationary contacts153 and 154 correspond to the side conductors 30 and 31 of Figure l. Y

Conductor 155 schematically represents' a portion of a circuit which isbeing Vprotected bythe Contact device including the contacts 152,153,and 154. The instantaneous current in Ythe conductor 155 is measured bya high quality current transformer 156, the output of which is impressedon a first circuit including the capacitor 157, Winding 158 and :asecond circuit comprising `a capacitor 159, resistor 160 and inductor161. The current through the coil 158 is forced, by proper circuitdesign of the components 157 through 161, to lead the current measuredat the output of the current transformer 156. The amount of this`advance will, as will be seen hereinafter, determine the pretrippingtime or the amount of time prior to the passage of a zero current valueat which the contact 152 will disengage the stationary contacts 153'and154 of Figure 10.

Winding 158 is the input winding of a` transductor 162 which may have acore or highly saturable type material. The transductor 162 is morespecically constructed to include a D.C. pre-excitation circuit,including the winding 163, D.C. source 164 and adjustable resistor 165,such that a voltage pulse wil-l be generated in the secondary winding166 when the primary current approaches a zero value.

In the event that the circuit protecting device, by way of example, isbeing utilized for over-current protection, then an over-current relay167A is provided as isA shown in Figure l0 to be normally open'and toclose upon the occurrence of a fault condition. Hence, upon theoccurrence ofa fault, the relay contact 167 closes andthe next pulseproduced in the winding 166 will reach the grid of the tube 16S tothereby make this vtubecouductive. The capacitor 169 which is normallychar-gedby the D.C. source 170 thus discharges through Ythe-primarywinding 171 of the high voltage air transformer 172.

assigns In view of voltage across the primary Winding 172, a highvoltage is impressed across the secondary winding 173 of thevtransformer 172 to thereby cause the tubes 174 and 175 to flash over.1t is to be noted that the high voltage on the winding 173 will be at avery high frequency to thereby make the time difference of discharge ofthe tubes 174 and 175 negligible.

Upon ilash over the tube 174, the capacitor 150 which is maintained in acharged condition by means of a D.C. source, including the transformer177 and the rectiiiers 178 through 181, may now discharge itself throughthe operating winding or drive coil 151 to thereby eiect contactdisengagement between the movable contact 152 and the stationarycontacts 153 and 154. Resistor 176 is provided in order to dampen andextinguish the high `frequency oscillations produced in the discharge ofthe capacitor 150.

It is to be specifically noted that the discharge of capacitor 150 toeiect contact disengagement or motion of the movable contact 152 iseiiiected only upon the delivery of a pulse from winding 166 after theclosure of the contact 167, this pulse occurring immediately prior tothe occurrence of a zero current value in the conductor 155. Hence, anyarc that is formed upon contact separation will be extinguished uponpassage of the current through its zero value.

Figure 12 shows `an embodiment of my novel contacting device wherein theguide member serves as the stationary contacts of the system. Figure l2more specically shows an operating coil 200 through which a-strongoscillatory capacitor discharge current may flow. A closed ring 201serves as the secondary coil of -a transformer having the primary coil200 and, as in the previous embodiments, is repelled by the strong shortcircuit forces developed between the currents owing in the coil 200 andthe ring 201. Operating coil 200 is supplied with this current by meansof the leads 202 and 203 which are connected to an energizing circuit.The movable contact 201 is then seen as cooperating with stationarycontacts 204, 205. Contacts 204 `and 205 as seen in Figures l2 and 12aare split into three parts by three slots and have a hole inside whichmakes them elastic in the radial direction in such a way as to make goodpositive contact to the movable contact 201. Hence, when the contactsare closed, the movable ring 201 is tightly jammed upon the outer coneof the contact 204 and makes good contact with the fixed contact 205which is elastic and compressed radially by the ring 201. A current thencan flow freely between the contacts 204 and 205 through thebridgingcontact 201.

Operating winding 200 of Figure l2 is more specifically shown as beingembedded in the potted compound body 206 which could be made from anepoxy resin filled with chopped berglass or a similar strong ller. Thispotted compound further contains the retaining rings 207 and 208. Rings207 and 208 may be made of stainless steel to add to the strength of thebody and may be slotted to prevent their forming a short circuit windingof their own.

Cylinder 209 is bolted to the upper electrode 205 by means of the bolts212, and contact 201 is disposed to travel into cylinder 209 -at greatvelocity when operating winding 200 is energized. When the movablecontact 201 disappears completely in the cylinder 209, there will be anopen gap between the electrodes 204 and 205 and a circuit is opened.

When the movable contact 201 travels inside of cylinder 209, itcompresses air in the cylinder which can escape only with difiicultyaround the rim of the movable contact 201. At the end of its upwardstroke, the movable piece 201 hits the reset piece 210 with a muchreduced shock because the compressed air has absorbed most of itskinetic energy which appears as heat in the surrounding air.

The ymoving ring 201 is then held in the uppermost position by theexpanding spring action of the upper' electrode 205. The movable contact201 can then be reset to its original position by lowering the resetpiece 2104i of the reset piece 210.

The co-ntact device of Figure l2 is seen as applied to a circuit inFigure 13 and the operating is graphically shown in Figure l5. Magneticcores 213 and 214 are lodged varound the conductor 204 which is aportion of the circuit being protected. They are made of a tape ofeasily saturable magnetic material wound in form of a toroidal core.Cores 212 and 213 are supplied with the bias windings 215 and 216 whichare energized from the DC. source 217 over a choke 218.

Figure 15a shows the current flowing through conductor 294 las i204. Theequivalent value of the bias cur rent in coil 215 is shown as i215, andthe equivalent bias current in coil 216 is shown as i215.

Considering the core 213, the bias current i215 and the main currenti204 compensate each other at the time t-l, which causes this core 213to unsaturate and a current pulse is now transformed into the outputcoil 219 as shown in Figure 15b. If the current i204 is smaller than thebias current owing into the coils 215 and 216, lthis transformation doesnot occur and no voltage is induced in the windings 219 or 220. Theoutput of coils 219 and 220 is rectified in the rectiers 221 and 222 andnegative voltage pulses like the one produced in the interval time ofthe time -1, t-2 of Figure 15b do not pass and therefore no voltageappears on the resistor 223.

Circuit connections are thus provided such that the output of therectiers 221 and 222 appears on the electrodes 224 and 225,respectively. The electrodes 224 and 225 are further constructed to bepositioned in a radio active gaseous medium as described in co-pendingapplication Serial No. 558,348, tiled January l0, 1956, and assigned tothe assignee of the instant application. A high voltage appearing oneither of these electrodes will flash them over to the electrode 226,which then can also draw an arc from the electrode 227. The electrodes226 and 227 are kept iat a high voltage by the capacitor 228 which ischarged by an auxiliary trickle charger which is not shown in Figure 13.

It is, therefore, seen that when the current i204 is larger than thebias current as shown in Figure 15a, a posi-tive Voltage pulse isinduced in winding 219 between the time interval t-S and f-4 as shown inFigure 15b. This will cause the gap 226-227 to iiash over and dischargecapacitor 228 through the operating winding 200.

yCurrent pulses which are induced in the negative direction are shown indotted lines in Figures 15b and 15e. Only the positive current pulses asshown by the solid line between t-3 and 144 of Figure 15b and 1&7 and fS of Figure 15C can flow through the rectiers 221 and 222. The resistor223 permits the reverse current of these rectiiers to iiow and preventsvoltage from appearing on the electrodes 224 and 225 during the negativehalf cycle.

By adequately choosing the magnitude of the bias current, it is seenthat it is possible to initiate contact interruption by advancing thecurrent pulses in such a way that at the time the current goes throughzero, the capaci-tor 228 will be discharged. 1f the contact interrupts ashort time before the current goes through zero, a small arc is formedin an extremely strong magnetic eld which makes this arc rotate veryrapidly around the vertical axis of the circuit breaker. This arc thenis burning between cold electrodes and its current goes through zeroalmost immediately after the arc is formed to quench the arc and preventfurther burning.

Figure 14 shows a further application of the embodiment of Figure l2. Aheavy current induction coil 230 having an air core mutual inductioncoil 231 with many turns is connected in series with the contacts 204and 205. If the rate of rise of'current in the coil 230 suddenly assumesa very high value, a high voltage pulse trodes 232 and 233. This, inturn, causesran arc between the electrodes 233 and 234 discharging thecapacitor 235 into the coil 200 which then opens the contact between theelectrodes 204 and 205 by displacing the sliding contact 201 upwardly.The circuit is now closed through the fuse 236 which is a relatively lowcurrent fuse and which blows almost instantaneously. During the timewhich the fuse 236 needs to interrupt, the contact 201 has traveled farenough upward to prevent any arc to form. Hence, circuit interruption isachieved without arcing between the main contacts 201, 204 and 205 andin the absence of special circuits to assure current interruptionimmediately prior to a Zero current value.

The principle of operation of my novel device be more fully understoodwith reference `to Figure 16 and Figure 1. The travel-time curve of adevice as shown in Figure 1 follows an equation:

where B and y are constants depending on the particular structureinvolved. Hence, the travel of the movable coil and contactstructureoccurs very sluggishly at iirst, but is at a very high rate once itstarts moving. Accordingly, it is essential that the contacts remain inengagement as long as the travel is slow and are separated only when thecontact moves at high speed.

Figure 16 shows the operation of the embodiment of Figure l. From themoment a current is initiated in coil 30, until the movable contact 32has moved upwards, far enough to be entirely disengaged from the fixedcontacts 30 and 31, there is a time delay of 160 microseconds (0.000160second). At this time the velocity of the Contact is 80 meters persecond. Accordingly, .when the contacts separate, the flash-overdistance increases rapidly which means that the flash-over voltageincreases with about the same rate. For this reason lthe recoveryvoltage, which rises less rapidly than the flash-over voltage, is unableto hash-over the opening circuit breaker.

A major drawback of the system described previously is the pooreiiiciency of the drive. Energy stored in the capacitor is released tobecome magnetic iield energy in the drive coil. Magnetic iield energyetects displacement of coils, causing decrease or" field' energy andincrease of kinetic energy of the moving bodies. Due to the inherentgeometry of the air coils, the energy transferred to kinetic form isrelatively small and the major part of the energy oscillates betweencapacitor andV variable inductor causing variable frequency oscillationwhich is a loss for the system. Practically attainable eiiiciency is onthe order of l to percent (ratio of kinetic energy to capacitor energy)and this low efliciency has several drawbacks:

(l) High energy capacitors are expensive and bulky,

(2) Waste magnetic energy tend to explode coils,

(3) Tripping circuits must handle Waste energy,

(4) Short relative motion uncouples coils which makes the systemineifective after a short travel.

Bolt 35 in Figures l, 2 and 3 and bolt 146 in Figure ll may be made from`a ferrite, i.e. a ferromagnetic ceramic material of the form XFe2O4where X stands for a metal such as manganese, iron, copper, nickel,cobalt, magnesium, lithium, etc. Multiple ferrites are known to havevery high initial permeability (of the order of 1000) and a resistivityseveral billion times higher than ordinary magnetic materials. A centerpost made of such a material or a bolt surrounded by a sleeve of such amaterial will carry a high density and high frequency magnetic ux toeffect a magnetically close coupling between the drive coil and thedriven coil. ln view of the highrpe'rmeability of this material, themagnetic energy contained in theinitial magnetic iield will be extremelylow, causing an extremely steep and high rate of increase of the driv- Ying current.

1d g. This in turn causes a rapidly increasing relative motion of thecoils. By virtue of the magnetic core in the coils the coupling betweenthem remains highV in spite of the increasing distance, effecting arepelling action over a much larger period of time and distance asobtainable without the magnetic core. y

Accordingly, the following advantages are had with the use of theferrite post:

(l) Drive capacitor, small, cheap,

(2) Lower stresses on coils,

(3) Faster initial motion of coils,

(4) Tripping circuit for lower energy,

(5) Drive maintained for substantial motion (fast acceleration of openbreaker).

ln the foregoing the invention has been described solely in connectionwith specic illustrative embodiments thereof. Since many variations andmodications of the invention Will now be obvious to those skilled in theart, I prefer to be bound not by the specific disclosures hereincontained, butonly by the appended claims.

I claim: Y

1. A contact device; said contact device comprising a pair of cooperablecontacts relatively movable intoV and out of engagement with oneanother, a iirst winding and energizingrneans for said rst winding; oneof said cooperable contacts being a second winding having an axiallength of substantially the same dimension as the radial 'thickness ofsaid second winding; said second winding being positioned to have acurrent induced therein responsive to energization of said iirstwinding; the magnetic fields of saidV rst and second windings being in`a direction to repel one another to thereby effect relative motionbetween said pm'r of cooperable contacts; said one of said cooperablecontacts forming said second winding being a ring having a constantcross-sectional area for conduction of currents induced therein by saidAfirst winding; the other of said pair of cooperable contacts engagingsaid ring on a surface thereof when said pair of cooperable contactsareV moved into engagement with one another; acceleration of said ringforming said second winding by a given forcebeing dependent only uponthe mass of said second Winding.-

2. A circuit interrupting device; said circuit interrupting devicecomprising a iirst and second contact, a iirst winding and an energizingmeans for said first winding; said rst contact being movable into andout of engagement with respect to said second contact; said ydrstcontact being a second winding having at least asingle turn; having anaxial length of substantially the same dimension as the radial thicknessof saidl second winding; said second winding being positioned to have acurrent induced thereinV responsive to energization of said iirstwinding; said rst contact being moved to a disengaged position withrespect to said second contact by the interaction between the magneticfields of said iirst and secondwindings; said first contact formingsaidsecond winding being a ring having a constant cross-sectional areafor conduction of currents induced therein by said iirst winding; saidsecond contact engaging said ring ona surfaceY thereof When saidVring'is moved into engagement with respect to said second contact;acceleration of said ring forming said second winding by a given forcebeing dependent only upon the'mass of said second winding; a guidemeans; said. guide means being constructed to'guide the motion of saidiirst contact when said rst contact is moved to a disengaged positionwith respect to said second contact'.

3. A circuit interrupting device; said circuit interrupting devicecomprising a rst andrsecond contact, a first winding and an energizingmeans for said first winding; said first contact being movable-into andout of engagement with respect to said second Contact; said first con-.tact being constructed to form a second winding having .asesinas atleast a single turn; said second winding being positioned to have acurrent induced therein responsive to energization of said firstwinding; said first contact being moved to a disengaged position withrespect to said second contact by the interaction between .the magneticfields of said first and second windings and a braking means; saidbraking means being constructed to brake the motion of said firstcontact when said first winding is energized and said first contact ismoved to said disengaged position; said braking means comprising acylinder constructed to have one end closed andthe other end open toreceive said movable contact whereby said movable contact effects apiston action in said cylinder to thereby compress the air between saidmovable contact and said closed end of said piston, said compression ofair being effective to oppose the motion of said first contact.

4. A circuit interrupting device; said circuit interrupting devicecomprising a first and second contact, a first winding and an energizingmeans for said first winding; said first contact being movable into andout of engagement with respect to said second contact; said firstcontact being constructed to form a second winding having at least asingle turn; said second winding being positioned to have a currentinduced therein responsive to energization of said first winding; saidfirst contact being moved to a disengaged position with respect to saidsecond contact by the interaction between the magnetic fields of saidfirst and second windings and a braking means; said braking means beingconstructed to brake the motion of said first contact when said firstwinding is energized and said first contact is moved to said disengagedposition; said braking means comprising a cylinder constructed to haveone end closed and the other end open to receive said movable contactwhereby said movable contact effects a piston action in said cylinder tothereby compress the air between said movable contact and said closedend of said piston, said compression of air being effective to opposethe motion of said first contact; said cylinder having an annulardepression in its inner diameter, the inner diameter of said annulardepression being effective to allow compressed air captured between theclosed end of said cylinder and said movable contact to escape when saidmovable contact passes said annular depression in its motion into saidcylinder.

5. A contact device; said contact device comprising a pair of cooperablecontacts relatively movable into and out of engagement with one another,a first winding and energizing means for said first winding; one of saidcooperable contacts being a second winding; said second winding beingpositioned to have a current induced therein responsive to energizationof said first winding; the magnetic fields of said first and secondwindings being in a direction to repel one another to thereby effectrelative motion between said pair of cooperable contacts; said one ofsaid cooperable contacts forming said second winding being a ring havinga constant cross-sectional area for conduction of currents inducedtherein by said first winding; the other of said pair of cooperablecontacts engaging said ring on a surface thereof when said pair ofcooperable contacts are moved into engagement with one another;acceleration of said ring forming said second winding by a given forcebeing dependent only upon the mass of said second winding; said firstwinding being coaxially positioned with respect to said second winding;said first winding being a spirally wound single conductor. i

6. A contact device; said contact device comprising a pair of cooperablecontacts relatively movable into and out of engagement with one another,a first winding and energizing means for said first winding; one of saidcooperable contacts being constructed to form a second winding; saidfirst and second windings being coaXially positioned with respect to oneanother; said first winding being substantiallsr embedded in asupporting insulating body; said supporting insulating body beingsupported by a shock-absorbing means; current being induced in saidsecond winding responsive to energization of said first winding; themagnetic fields of said first and second windings being in a directionto repel one another to thereby effect relative motion between said pairof cooperable contacts; the energy of motion imparted to said firstwinding due to the motion of said second winding being absorbed by saidshock-absorbing means.

7. A contact device comprising a stationary contact and a concentricmovable contact; said movable contact being a short circuited windinghaving a constant crosssectional area for conduction of current inducedtherein by said first winding; lhaving a fiat ring-shape; all of themass of said fiat ring-shaped winding being operable as a winding; saidmovable contact being movable into and out of concentric contactengagement with respect to said stationary contact; an operating windingand an energizing means therefor; said operating winding being disposedto induce current in said short circuited winding formed by said movablecontact responsive to energization of said operating winding to therebymove said movable contact to a disengaged position with respect to saidstationary contact; acceleration of said movable contact to saiddisengaged position by a given force being dependent only upon the massof said movable contact; a latching means; said latching means beingconstructed to maintain said movable contact in the disengaged positionwhen said movable contact is moved thereto.

8. A contact device comprising a stationary contact and a concentricmovable contact; said movable contact being a short circuited windinghaving a constant crosssectional area for conduction of current inducedtherein by said first winding; all of the mass of said movable contactbeing operable as a winding; said movable contact being movable into andout of concentric contact engagement with respect to said stationarycontact; an operating winding and an energizing means therefor; saidoperating winding being disposed to induce current in said shortcircuited winding formed by said movable contact responsive toenergization of said operating winding to thereby move said movablecontact to a predetermined contact position; acceleration of saidmovable contact toward said predetermined contact position beingdependent only upon the mass of said movable contact; said stationarycontact being constructed to comprise first and second portions lying inthe plane of said stationary contact and movable contact; a biasingmeans; said first and sec-ond portions being connected to said biasingmeans and being biased toward said movable contact to effect strongcontact engagement with said movable contact.

9. A contact device; said contact device comprising a pair of cooperablecontacts relatively movable into and out of engagement with one another,a first winding and energizing means for said first winding; one of saidcooperable contacts forming a second winding; having a generally fiatring-shape; said second winding being positioned to have a currentinduced therein responsive t0 energization of said first winding; themagnetic fields of said first and second winding being in a direction torepel one another to thereby effect relative motion between said pair ofcooperable contacts; said one of said cooperable contacts forming saidsecond winding being a ring having a constant cross-sectional area forconduction of currents induced therein by said first winding; the otherof said pair of cooperable contacts engaging said ring on a surface`thereof when said pair of cooperable contacts are moved into engagementwith one another; acceleration of said ring forming said second windingby a given force being dependent only upon the mass of said secondwinding; said first and second windings being magnetically coupled by Iamagnetic member.

10. A contact device; said contact device comprising a pair ofcooperable contacts relatively movable into and 19 out of engagementwith one another, a first winding and energizing means for said firstWinding; one of said co'- operable 'contacts forming a second windinghaving an axial length of substantially the same dimension as the radialthickness of said second winding; said second winding being positionedto have a current induced therein responsive to energization of saidfirst winding; the magnetic fields of said first andtsecond windingsbeing in a direction to repel one another to thereby effect relativemotion between said pair of cooperable contacts; said one of saidcooperable contacts forming said second winding being a ring having aconstant cross-sectional area for conduction of currents induced thereinby said first Winding; the other of said pair of cooperable contactsengaging said ring on a surface thereof when said pair of cooperablecontacts are moved into engagement with one another; acceleration ofsaid ring forming said second winding by a given force being dependentonly upon the mass of said second winding; a ferrite member; said firstand second windings being coaxially'positioned on said ferrite member.

11. A contacting device comprising a movable contact and a complementarycontact engageable by said movable contact; said movable contact beingformed of a conductive electrically energizable winding generating amagnetic field when energized and means positioned for generating amagnetic field 'for repelling said first mentioned magnetic field; saidmovable contact forming a ring having a constant cross-sectional `areafor conduction of current induced therein by the magnetic field of saidmeans positioned for generating a magnetic field; acceleration of saidmovable contactto said disengaged position by a given force beingdependent only upon the mass of said movable contact; said complementarycontact engaging said movable contact along the outer periphery of saidmovable contact.

Y 12. A contact device; said contact `device comprising a pair ofcooperable contacts movable into and out of engagement with one another;one of said cooperable contacts being constructed to form a windinghaving at least a single turn and a means energizable toV produce amagnetic field and initiate vcurrent flow in said winding; said pair vofcooperable contacts being in a normally engaged position; said pair ofcooperable 'contacts being moved to a disengaged position Vwith respectto one another responsive Vto the interaction between a magnetic fielddue to current iiow in said winding and the magnetic field produced bysaid means; said one of said pair of cooperable contacts forming atleast said single turn forming a ring having a constant cross-sectionalcurrent carrying area for current induced in said ring by the magneticfield of said means energizable to produce a magnetic field;acceleration of said one of said pair of cooperable contacts for a givenforce being dependent only upon'the mass of said one of said pair ofmovable contacts; said pair of cooperable contacts normally engagingeach other along the outer periphery of said one of said cooperablecontacts constructed to form a winding. n

13. A circuit interrupting device; said 'circuit interrupting devicecomprising a first and Asecond contact, a

first winding and anv energizing means for said first windf ing; saidfirst contact being movable into and out of engagement with respect tosaid second contact; said first contact being a second winding having atleast a single turn; said second winding being positioned to have acurrent induced therein responsive to energization of said firstWinding; said first contact being moved to a disengaged position withrespect to said second contact by the interaction between the magneticfields of said first and second windings; said iirst contact formingsaid second winding being a ring having a constant cross-sectional areafor conduction of currents induced therein by said first winding; saidsecond contact engaging said ring on a surface thereof when said ring ismoved into engagement with respect to said second contact; accelerationof said `ring yforming said second winding by a given force beingdependent only upon the mass of said second wind-I ing; aV guide means;said guide means being constructed to guide the motion of said firstContact when said first contact is moved to a disengaged position withrespect to said second contact; said first and second contacts engagingone another along the outer periphery of said second contact.

14. A contacting device comprising a movable conctact anda complementarycontact; said complementary contact being movable between a first andsecond position; lsaid complementary contact engaging said movablecontactfwhen said complementary contact is in said first position; saidmovable contact and said complementary contact being'disengaged whensaid complementary contact i's in said second position; said movablecontact being an electrically energizable sho-rt-circuited winding;means for generating y'a magnetic field for inducing Va circulaitingcurrent in said movable contact to impart motion to `said movablecontact; and 'operating means operatively connectable between saidcomplementary contact and said movable contact; said operating meansbeing operable to move said complementary contact to said secondposition responsive 'to movement of said movable contact whereby saidcontacting device is trip-free because of said movement of 'saidcomplementary contact to said second position responsive tor saidmovement of said movable contact.

References Cited in the file of this patent UNITED STATES PATENTS370,573 Thomson Sept. 27, 1837 1,066,081 Coleman July 1, 1913 1,672,193Basonl June 5, 1923 1,941,273 Prince Dec. 26, 1933 1,980,736 TrofimovNov. 13, 1934 2,427,750 Snyder Sept. 23, 1947 2,457,617 Walle Dec, 2S,1948 2,5 69,353 Ta'liaferro Sept. 25, 1951 2,5903302 Evans Mar. 25, 19522,601,473 Weynsbergen lune 24, 1952 2,691,128 Wegener Oct. 5, 19542,773,221 Shaw Dec. 4, 1955 2,781,457 Urban Feb. 12, 1957

